Corrosion-resisting cobalt-chromium-tungsten alloy



United States Patent i 3,425,821

Patented Feb. 4, 1969 to 1% manganese, 2535% chromium, 3l2.9% CORROSION f g CHROMIUM tungsten, 0.26% copper, 06% molybdenum, balance balt.

TUNGSTEN ALLOY Anton Baumel, Lank (Lower Rhine), Germany, assignor A speclfll advafltage of the 1atter P P to to Gebr. Bohler & Co., Aktiengesellschaft, Vienna, i f g id oslstancte l eslgesfll'l that they; Au tria can e use or we -sur acmg wit out t e orma H 0 No Drawing. Continuation-impart of application Ser. cracks even when the base material is not preheated. The

g zg g g k z g This application Julie alloys of this class are also improved in corrosion resist- 3 f' r ance by an addition of copper and molybdenum without i g g g gyg fg 1963 10 a reduction in wear resistance'It has also been found Us 8 Claims that an addition of nickel enables a further increase in b 19/02 the corrosion resistance of alloys having a high or medium wear resistance.

This invention relates to an improvement in the copperand molybdenum-containing alloys of the class disclosed ABSTRACT OF THE DISCLOSURE in my copending application Ser. No. 372,089 filed June In a cobalt-chrominm-tungsten alloy, a portion of the 2, 1964, and issued as US. Patent 3,307,939, which concobalt is substituted with from -20% nickel to tain about 2.0% carbon, 1% silicon, 1% manganese, markedly increase the corrosion resistance of the alloy. chromium, 14% tungsten, 46% cobalt, 4% molyb- 20 denum and 2% copper. Three improved alloys having a high Wear resistance and containing 2.5%, 10% and This application is in part a continuation of application 20% nickel, respectively, the cobalt content being corre- Ser. No. 404,951, filed Oct. 19, 1964, and entitled, Corspondingly reduced, are described in Table 1.

Melt No. C Si Mn Cr W Ni 00 Mo Cu Fe 0. 14 0. 32 25. 76 14. 60 10. 7 40. 66 3. 42 1. s3 0. 22 0. 4e 0. 32 2s. 00 16. 15 19. s 27. 90 3. so 2. 11 o. 20 1.98 0. 97 34. 93 20. 0o 2. 2e. 86 s. so 5. 97 0. 1s

1 Calculated as the balance.

rosion-Resisting Cobalt-Chromium-Tungsten Alloy now The replacement of nickel for cobalt alters the hardabandoned. 3r ness value at room temperature only to a slight extent,

According to my United States Patent No. 3,307,939, a from approximately Rockwell C 54-55 for the nickelthe corrosion resistance of hard alloys containing cobalt, free alloy or alloys with a low nickel content to Rockwell chromium and tungsten can be improved by an addition C 52-54 for alloy 1 containing 10% nickel and 50-52 of copper and, if desired, molybdenum. For instance, an Rockwell C for alloy 2 containing 20% nickel. For this alloy having the following composition has a particularly 4O reason an appreciable reduction of the wear resistance high corrosion resistance and a virtually unreduced wear as a result of the replacement of nickel for cobalt is not resistance: 22-25% carbon, 3032% chromium, 13- to be expected. 20% tungsten, 39-47% cobalt, up to 1% manganese, up Alloys 1, 2 and 3 in as-cast and as-Welded states were to 1%..silicon, 0.26% copper and 06% molybdenum, subjected to weight loss tests at room temperature and specifically 2.2% carbon, 30% chromium, 14% tungsten, boiling temperature in 10% hydrochloric acid, and 20% 46% cobalt, 4% molybdenum, 2% copper, up to 1% 45 sulfuric acid, and 30% nitric acid. The results of these manganese, up to 1% silicon. tests are compiled in Table 2.

TABLE 2 I [Weight losses in gJsq. m./h. of the alloys of Table 1 in ascast and sis-welded states in hydrochloric,

sulfuric and nitric acids] Corrosive Test Alloy 1 Alloy 2 Alloy 3 Agent Temp.

As-cast As welded As-cast As-welded As-cast As-welded R.T Room temperature, B.T= Boiling temperature.

A comparison of these weight losses with those of the The alloys falling within the above-mentioned analysis nickelfree alloys as stated in Table 3 of the above-noted ranges are hard alloys having a high wear resistance. patent shows that the addition of nickel results in a fur- Hard alloys having a medium Wear resistance may also ther increase of the corrosion resistance. On an average, be made corrosion-resisting by an addition of copper and, 65 the addition of between 2.5% and 20% nickel results if desired, molybdenum. Their composition is within the in a decrease of the weight losses to between one half following limits: 0.72.2% carbon, up to 2% silicon, up and one third in hydrochloric acid and sulfuric acid.

TABLE 3.-CHEMICAL COMPOSITION OF COBALT-CHROMIUM-TUNGSTEN ALLOYS CON- TAINING COPPER AND MOLYBDENUM Alloy No. C Si Mn Cr W Go 1 Mo Cu Fe 1 Calculated as the balance.

TABLE 4 Content 01- 10% Hydrochloric Acid Sulfuric Acid Alloy N 0. Mo Cu Room temp. Boiling temp. Room temp. Boiling temp.

C W C W C W C W O=as cast, W=as-welded.

An alloy having a composition of 2.2% carbon, 1% silicon, 1% manganese, 30% chromium, 14% tungsten, 10% nickel, 36% cobalt, 4% molybdenum, and 2% copper appears to be most suitable for practical use as a corrosion-resisting hard alloy containing copper, molybdenum and nickel.

A somewhat smaller corrosion-resisting effect is achieved with a nickel content below 10%.

A similarly favorable result Was achieved with alloys having a medium wear resistance by an addition of nickel. The analysis ranges of such hard alloys are 0.7-2.2% carbon, O-2% silicon, 0-1% manganese, -35% chromium, 312.9% tungsten, 2.5 to 10% nickel, 06% molybdenum, 0.2-6% copper, balance cobalt.

An alloy having the following composition has been found to be particularly desirable:

1.2% carbon, 1.1% silicon, 0.15% manganese, chromium, 4% tungsten, 7% nickel, 3.3% molybdenum, 1.6% copper, balance cobalt.

A comparison of the weight losses in hydrochloric and sulfuric acids shows that in the hard alloys of this type, having a medium wear resistance owing to reduced carbon and tungsten contents, the addition of copper, molybdenum and nickel results in the same high corrosion resistance as in a hard alloy having a high wear resistance owing to higher carbon and tungsten contents. The alloys tested had the following composition:

(a) Alloy of medium wear resistance: 1.20% carbon, 1.0% silicon, 0.09% manganese, 27.7% chromium, 4.9% tungsten, 6.0% nickel, 3.43% molybdenum, 1.48% copper, 0.35 iron, balance cobalt.

(b) Alloy of high wear resistance: 2.23% carbon, 1.28% silicon, 0 .08% manganese, 27.1% chromium, 13.5% tungsten, 6.1% nickel, 3.53% molybdenum, 1.50% copper, 0.7% iron, balance cobalt.

Weight losses in g./sq. m./h. of alloys (a) and (b) in hydrochloric, sulfuric and nitric acids Corrosive Test temperature Alloy (a) Alloy (b) agent 10- E180; Room temperature 0.01 0.01 Boiling temperature.-. 0. 53 0.59 20- 11:80; Room temperature- 0.015 0.018

Boiling temperature 1. 20 1. 15 10- E01 Room temperature 0.75 0.83

Bolling temperature 135 142 chromium, 3-20% tungsten, 0-6% molybdenum, 0.2-6% copper, 25-20% nickel, balance cobalt.

What is claimed is:

1. A corrosion-resisting cobalt-chromium-tungsten a1- loy consisting essentially of 0.7-2.5% carbon, up to 2% silicon. up to 1% manganese, 25-35% chromium, 3-20% tungsten, up to 6% molybdenum, 0.2-6% copper, 2.5- 20% nickel, balance cobalt.

2. A corrosion-resisting cobalt-chromium-tungsten alloy consisting essentially of 22-25% carbon, 30-32% chromium, 13-20% tungsten, up to 1% manganese, up to 1% silicon, 0.2-6% copper, up to 6% molybdenum, 2.5- 20% nickel, balance cobalt.

3. A corrosion-resisting cobalt-chromium-tungsten alloy consisting essentially of 07-22% carbon, up to 2% silicon, up to 1% manganese, 25-35% chromium, 3- 12.9% tungsten, up to 6% molybdenum, O.2-6% copper, 25-20% nickel, balance cobalt.

4. A corrosion-resisting cobalt-chromium-tungsten allov consisting essentially of 2.2% carbon, 30% chromium, 14% tungsten, 36% cobalt, 4% molybdenum, 2% copper, up to 1% manganese, up to 1% silicon, and 10% nickel.

5. A corrosion-resisting cobalt-chromium-tungsten allov consisting essentially of 1.2% carbon, 1.1% silicon, 0.15% manganese, 30% chromium, 4% tungsten, 7% ickel, 3.3% molybdenum, 1.6% copper. balance cobalt.

6. A corrosion-resisting cobalt-chromium-tungsten alloy consisting essentially of 0.7-2.5% carbon, up to 2% silicon, up to 1% manganese, 25-35% chromium, 3-20% tungsten, up to 6% molybdenum, 0.2-6% copper, 6-20% nickel, balance cobalt.

7. A corrosion-resisting cobalt-chromium-tungsten alloy consisting essentially of 2.23-2.30% carbon, 0.42- 1.28% silicon, 0.08-0.32% manganese, 27.l28.46% chromium, 13.5-16.15% tungsten, 6.1-19.3% nickel, 3.3- 3.39% molybdenum, 1.5-2.11% copper, 02-07% iron, and 27.9-37.66% cobalt.

8. A corrosion-resisting cobalt-chromium-tungsten alloy consisting essentially of 1.2% carbon, 1.0-1.1% silicon, 0.09-0i15% manganese, 27.7-30% chromium, 4- 4.9% tungsten, 6.0-7% nickel, 3.3-3.43% molybdenum, 1.48-1.6% copper, up to 0.35% iron, balance cobalt.

References Cited UNITED STATES PATENTS 1,630,448 5/1927 Oertel -171 3,183,082 5/1965 Konecsni 75l l 3,205,055 9/1965 Laurent et al. 75-171 3,307,939 3/1967 Baumel 75171 RICHARD O. DEAN, Primary Examiner. 

